In a conventional integrated drive generator system, a drive shaft connectable to an output shaft driven by an aircraft engine is connected to a mechanical differential, with the differential having an output connected to drive the generator. A variable speed transmission, such as a hydrostatic transmission or log, is associated with the mechanical differential and controlled to modify the output of the differential, as required, whereby the input speed to the generator remains constant even though the speed of the drive shaft may vary. There are a variety of structural arrangements for a constant speed drive and generator system, such as those shown in Baits U.S. Pat. No. 3,576,143 and Aleem U.S. Pat. No. 3,786,696.
The continuing growth of aircraft engine technology demands that accessory components be afforded with lighter, more efficient systems with narrow frontal areas, thereby minimizing aerodynamic drag losses. Serviceability of the accessories also is of growing concern. The integrated drive generator is a primary engine accessory. Conventional integrated drive generators have separate centerlines or axes for the various components thereof, particularly the three main components comprising the differential, the generator and the hydraulic pump and motor assembly, sometimes called the hydraulic log. Problems associated with such integrated drive generators include a fairly large frontal area which increases engine nacelle size and, thus, engine aerodynamic losses; increased heat rejection because of the many rotating surfaces exposed to the oil sump; added weight and servicing requirements associated with cooling and maintaining an independent oil supply; and added weight from part functions not optimally integrated.
This invention is directed to solving the above problems and satisfying the needs of changing aircraft engine technology.